Head feels intensely dizzy and my body gets woozy after watching TV for an hour and standing up from the couch?

This has been going on for a long time now. Last time it happened was today (an hour ago). After sitting on the couch for two hours watching TV, I stand up and immediately my head feels really dizzy and my vision starts to blur for maybe about ten to twenty seconds. Then I go back to normal and I don't feel all woozy anymore but I still have a minor headache right now. Any idea why this is happening to me? and this has been happening to me for maybe almost a year...